Urgent help needed! Is this adaptation of the coroutine tutorial correct, or did I miss something? `...

# coroutines

[voddan]

Urgent help needed!
Is this adaptation of the coroutine tutorial correct, or did I miss something?

import org.springframework.util.concurrent.ListenableFuture
import org.springframework.util.concurrent.ListenableFutureCallback

public suspend fun <T> ListenableFuture<T>.await(): T = suspendCancellableCoroutine { cont: CancellableContinuation<T> ->
    val callback = ContinuationCallback(cont)
    this.addCallback(callback)
    cont.invokeOnCompletion {
        callback.cont = null // clear the reference to continuation from the future's callback
    }
}

private class ContinuationCallback<T>(@Volatile @JvmField var cont: CancellableContinuation<T>?) : ListenableFutureCallback<T> {
    @Suppress("UNCHECKED_CAST")
    override fun onSuccess(result: T?) { cont?.resume(result as T) }
    override fun onFailure(t: Throwable) { cont?.resumeWithException(t) }
}

[Vsevolod Tolstopyatov [JB]]

It’s fine.
You can optimize it a bit by adding if (isDone) return get() before suspendCancellableCoroutine

[voddan]

Thanks for verifying! I stumbled across a ridiculous bag in my system and the logs suggest that two suspend methods executed in the reverse order of how they are written. Glad to know it is not about my await 🙂